Activity of soybean lipoxygenase isoforms against esterified fatty acids indicates functional specificity
Activity of soybean lipoxygenase isoforms against esterified fatty acids indicates functional specificity
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DOI：
10.1006/abbi.2000.2269
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发表时间：
2001-04-01
影响因子：
3.9
通讯作者：
Grimes, HD
中科院分区：
文献类型：
--
作者：
Fuller, MA;Weichert, H;Grimes, HD
大豆（Glycine max L.）营养组织中存在至少五种脂氧合酶同工酶。这些蛋白质中的四个已经定位于脉旁叶肉，一层被认为在同化物分配中起作用的细胞。为了确定脂氧合酶同工酶在大豆植物中的作用，将叶脂氧合酶克隆到细菌表达载体中并在大肠杆菌中表达。然后对重组脂氧合酶的底物偏好性、最常见的植物脂氧合酶底物亚油酸和α-亚麻酸的pH曲线以及与底物亚油酸、α-亚麻酸、花生四烯酸、γ-亚麻酸和三酰甘油三亚油酸甘油酯的反应产物进行表征.所有五种酶被证明是（ISS）-脂氧合酶对亚油酸。这些测定的结果还表明，这些同工酶中的两种对酯化脂肪酸基团具有高度活性，例如在三酰基甘油中发现的那些。来自经受库限制条件的植物的叶的脂质分析表明，大豆叶脂氧合酶在体内对游离脂肪酸和酯化脂质都是活性的，并且在叶组织中发现的脂氧合酶产物的量显示出与叶中脂氧合酶的水平正相关。这些酶在脉旁叶肉的假定作用的影响进行了讨论。(C)北京：科学出版社.
In soybean (Glycine max L.) vegetative tissue at least five lipxoygenase isozymes are present. Four of these proteins have been localized to the paraveinal mesophyll, a layer of cells that is thought to function in assimilate partitioning In order to determine the role of the lipoxygenase isozymes within the soybean plant, the leaf lipoxygenases were cloned into bacterial expression vectors and expressed in Escherichia coti. The recombinant lipoxygenases were then characterized as to substrate preference, pH profiles for the most common plant lipoxygenase substrates, linoleic acid, and alpha -linolenic acid, and the reaction products with the substrates linoleic acid, alpha -linolenic acid, arachidonic acid, gamma -linolenic acid, and the triacylglycerol trilinolein. All five enzymes were shown to be (ISS)-lipoxygenases against linoleic acid. The results of these assays also indicate that two of these isozymes are highly active against esterified fatty acid groups, such as those found in triacylglycerols. Lipid analysis of leaves from plants subjected to sink limitation conditions indicates that the soybean leaf lipoxygenases are active in vivo against both free fatty acids and esterified lipids, and that the quantities of lipoxygenase products found in leaf tissue show a positive correlation with the level of lipoxygenase in the leaf. Implications for the putative role of these enzymes in the paraveinal mesophyll are discussed. (C) 2001 Academic Press.